Steel-making process.



UNITED STATES PATENT. orrron.

GEORGE G. MGMURTRY, OF NEW CORPORATION, OF HOIBOKEN,

No Drawing.

T 0 all whom it may Be it known tha 'IRY, a resident of tan, city, county, and State have invented certain new provements in Ste YORK, N. Y., ASSIGNOR T0 UNITED STATES STEEL NEW JERSEY, A CORPORATION OF NEW J ERSEY;

\ STEEL-MAKING PROCESS.

Specification of Letters Patent.

Application filed January 27, 1915. Serial No. 4,578.

t I, GnoRcE 'G', MGMUR- the borough of Manhatof New York, and useful Imel-Makmg Processes, of

which thefollowing is a specification. My invention aims to obtaln from co1nparatively cheap materials a steel of the finest quality,

or at least of a quality superion to that heretofore obtained from such materials.

For this purpose I combine the basic process which is applicable to the refinin of comparatively cheap iron and steel containing a considerable percentage of phosphorus, with the'acid process which is known to produce a higher degree of refinement but which has heretofore been applied only to expensive iron and steel, low in phosphorus.

The basic process of making steel'consists in having a molten over a molten bath By the addition of phosphorus are removed blanket of basic slag of. iron or nnpure steel.

oxids, such impurities as by first. oxidizing the impurity and entraining it in the slag.

This operation may hearth furnace, or i In the electric steel may be performed ten bath of metal a be carried on in an open in: an electric furnace.

process, further refining,

by havingover the molmolten basic slag free from oxids and having a strictly reducing condition.

This makes possible the removal of sulfur as calcium sulfid and the reduction of oxids to metals-which unite with the steel.

The acid process may hkewise be conducted either in the electric) furnace.

in the open hearth furnace or It has certain advantages in that the slag in the acid process is of such a nature as to allow impurities to rise out of the steel by their buoyancy and become incorporated in the slag.

The relative advantages acid processes hav of the basic and e been long recognized,

but hitherto it has been thought necessary to conduct the basic process in a furnace and the acid process in an furnace.

basic lined acid lined I purpose to combine the basic and acid processes material which is so, to the different and to use a furnace lining of a neutral. or substantially slags. Such a material, oxid of zirconium known conia. This material has slag covering.

; nated.

ployed. This material may be used in the form of bricks laid up' to constitute the linin or may be spread into place in plastic condition and shaped as desired.

In using an open hearth furnace, I proceed as follows: j

In an open hearth furnace, lined with a neutral refractorymaterial, such as zirconia, I place pig iron and scrap, or' other metallic materials, with limestone and oxids, for instance, an oxid of iron, commercially called iron ore. The/lime and ore form a slag which oxidizes and eliminatesfrom the bath phosphorus, silicon, manganese, carbon, etc. This slag is removed from the metaLeither by sc'aping off the slag or by tilting the furnace and allowing it to flow away, or by removing the molten metal from the furnace and replacing it in the furnace minus the I then add a second slag. acid in character, consisting, for instance, of silica sand, and finish the operation in the usual manner of working the acid open hearth process.

In using an electric furnace, I proceed as follows:

I place in an electric furnace, which is lined with a neutral refractory material, such as zirconia, the. metal to be treated. I provide a slag, consisting of lime and iron ore, by which various metalloids are elimi- I then remove the slag in one of the ways mentioned in connection with the open hearth procedure. I then add a slag very basic in character. consisting usually of lime and fluorspar. but which may also contain 'dered carbon or similar reducing agent thrown on the slag combines with the sulfur f of the calcium sulfid therein and prevents its return to the bath. There is thus a continued extraction of sulfur from the bath, without the usual returning of the same. and

consequently a desulfurization of the bath."

I then remove this basic slag from the bath of molten metal and thus get rid of the 'Si'flfur, leaving in the bath any metals which may have-been reduced from their oxids. I then add an acid slag, consisting for instance of silica sand, and proceed in the lal way to finish the refining according o'the acid process, except that in this case the heat necessary is obtained from the electric arc instead of by the combustion of gases in the melting chamber of an open hearth furnace.

I find that the steel obtained by treating I according to the basic process first and then according to the acid process is of a superior quality. The new process is cheaper than the old acid process, because in the acid process as formerly worked it was necessary to make the steel from costly materials of great purity, whereas by my combination process I start with cheaper materials and ulticonsists in treating it first with a basic slag and then with an acid slag in the same furnace having a lining of zirconia.

In witness whereof, I have hereunto signed my name in the presence of two subscribing witnesses.

GEORGE e. McMUR'lRY.

Witnesses I D. ANrHoNY USINA, LULA STUBEN vonL.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents.

Washington, D. C. I 

